JPH0733378Y2 - Sodium-sulfur battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial field of application] The present invention relates to a sodium-sulfur battery, and more specifically, it can increase the bonding strength with a bottomed cylindrical solid electrolyte and is a thermocompression bonding member. The present invention relates to a sodium-sulfur battery that can effectively prevent squeeze out.

[Prior Art] A sodium-sulfur battery has molten metal sodium as a cathode active material on one side and molten sulfur as an anode active material on the other side, and both have a selective permeability to sodium ions. Isolate with beta-alumina solid electrolyte, 300-350
It is a high temperature secondary battery operated at ℃.

The structure of such a sodium-sulfur battery is, for example, the second one.
As shown in the figure, a cylindrical anode container 2 containing a conductive material for an anode 1 such as carbon felt impregnated with molten sulfur S as an anode active material, an upper end of the anode container 2 and an insulation made of alpha alumina. With a cathode metal container 4 which is connected through the insulating ceramics ring 3 and stores molten metal sodium Na, and a function of being joined to the inner peripheral portion of the insulating ceramics ring 3 and selectively transmitting sodium ions Na ⁺ And a bottomed cylindrical beta-alumina solid electrolyte tube 5 having a bottom. Further, a cathode tube 7 having a beta-alumina solid electrolyte tube 5 extending downward through the cathode metal container 4 to the vicinity of the bottom portion is penetratingly supported in the central portion of the upper lid 6 of the cathode metal container 4.

In the sodium-sulfur battery having the above structure, during discharge, molten metal sodium releases an electron to become a sodium ion, which penetrates through the beta-alumina solid electrolyte and moves to the anode side, passing through the sulfur of the anode and an external circuit. It reacts with the incoming electrons to form sodium polysulfide, generating a voltage of about 2V. On the other hand, at the time of charging, the reaction of generating sodium and sulfur occurs contrary to the discharging.

[Problems to be solved by the invention] In such a sodium-sulfur battery, the temperature change is large between when the battery is operating (300 to 350 ° C) and when it is not operating (room temperature). It is urgently necessary to prevent the destruction and damage of the joint portion due to the difference in thermal expansion between the insulating ceramic ring and the insulating ceramic ring.

Further, during the thermocompression bonding of the insulating ceramics ring and the cathode metal container, a thermocompression bonding member such as aluminum may sometimes protrude (flow out), and prevention of this is also important. That is, the sodium-sulfur battery is formed by assembling the unit cells to form a battery, but it is more efficient to pack the unit cells together in terms of volume efficiency. In the case of assembling the unit cells, the unit cells are usually housed in a sheath can metal container as a structure in which an insulating material such as mica sheet is wound. Here, if the thermocompression bonding member is squeezed out during storage of the unit cell, the mica sheet of the insulating material may be damaged and may come into contact with the metal container of the sheath can to cause a short circuit between the negative and positive electrodes.

[Means for Solving the Problems] Therefore, in order to solve the above-mentioned conventional problems, it is important for the present inventor to make an insulating ceramic ring bonded to a bottomed cylindrical solid electrolyte into a specific shape as a result of various studies. That is, the present invention has been completed and the present invention has been completed.

That is, according to the present invention, the anode container containing the molten sulfur and the cathode metal container containing the molten metal sodium are connected and insulated via the insulating ceramic ring, and the inner periphery of the insulating ceramic ring is connected to the insulating ceramic ring. In a sodium-sulfur battery in which a bottomed cylindrical solid electrolyte is fixedly bonded by a bonding glass, and the insulating ceramics ring is thermocompression bonded to the cathode metal container via a thermocompression bonding member, the insulating ceramics The ring forms a taper shape in which a portion to be joined toward the bottom direction of the solid electrolyte expands, and the insulating ceramic ring is on the outer peripheral side to the opening side of the solid electrolyte to prevent the thermocompression bonding member from protruding. Forming a protrusion for use in the sodium hydroxide, and the upper surface of the protrusion is in contact with the cathode metal container. Yellow battery, is provided.

[Operation] In the sodium-sulfur battery of the present invention, since the insulating ceramic ring has the specific shape as described above, when the glass is bonded, the glass ring is installed on the tapered portion of the insulating ceramic ring for bonding work. The efficiency can be improved, and the residual stress at the joining end at the time of joining and the joining strength such as cantilever bending strength can be increased.

Further, since the insulating ceramic ring has a protrusion on the outer peripheral side on the opening side of the solid electrolyte, it prevents the outflow of the joining member such as aluminum during the thermocompression bonding of the insulating ceramic ring and the cathode metal container. be able to. Furthermore, in the firing step during the glass thin layer forming treatment step for thermocompression bonding, stack firing can be performed by utilizing the protrusions of the insulating ceramic ring, and the firing step can be made more efficient.

[Embodiment] The present invention will be described below in more detail based on the illustrated embodiments, but the present invention is not limited to these embodiments.

FIG. 1 is a schematic view showing an embodiment of a joint between an insulating ceramics ring and a bottomed cylindrical solid electrolyte according to the present invention. An insulating ceramics ring 11 is provided around the open end of the bottomed cylindrical solid electrolyte 10. Are bonded by the bonding glass 12.

The insulating ceramics ring 11 is formed with a tapered portion 13 having an angle of 20 ° and a length of 3 mm at a portion to be joined to the bottom side of the joined portion to the bottomed cylindrical solid electrolyte 10.

By bonding the insulating ceramics ring 11 having such a specific shape, the bonding strength such as the residual stress during bonding and the cantilever bending strength at the bonding end can be increased, and the damage of the bonding part can be prevented.

Further, 14 indicates a protrusion formed on the outer peripheral side of the insulating ceramics ring 11 in the opening direction of the bottomed cylindrical solid electrolyte 10, and at the time of thermocompression bonding between the insulating ceramics ring 11 and the cathode metal container, Prevents the outflow of joining members such as aluminum.

Next, as the bonding glass 12, one having a smaller thermal expansion coefficient than the insulating ceramics ring 11 and the solid electrolyte 10 is preferably used, and for example, borosilicate glass or the like is preferably applied.

The transition temperature of the bonding glass is 550 to 6 from the viewpoint of stable bonding between the insulating ceramic ring 11 and the solid electrolyte 10.
It is preferably 00 ° C.

The solid electrolyte 10 is a sodium ion conductive one, and β-alumina, β ″ -alumina or other beta-alumina is used, and the insulating ceramics ring 11 has an insulating alpha alumina,
Spinel and zirconia can also be used.

The insulating ceramics ring 11 and the solid electrolyte 10 are joined by
It is carried out by charging a bonding glass ring into the bonding portion or applying a glass paste to the bonding portion and heating the glass paste at about 1000 ° C. for about 15 minutes.

FIG. 2 is a schematic view showing stacking and firing using the insulating ceramic ring of the present invention, the radial width is 6 mm and the length is 11 mm.
The glazing glass 15 for thermocompression bonding is applied to the insulating ceramic ring 11 and is baked in a furnace.

Approximately 10 ~ 20 by sol-gel method on the plane of 14 protrusions with a width of 1.15mm and a height of 0.75mm of the insulating ceramic ring 11.
A glass coating 15 is formed by applying mg glazing glass. Place the taper portion 13 downward on the firing table 16 and
Ten insulating ceramic rings 11 are stacked, set in a furnace, and fired at 900 to 1000 ° C. for about 1 hour.

In this way, by firing the insulating ceramics ring 11 by stacking it using the protrusions 14, it is possible to improve the efficiency of the firing process of the glazing glass.

FIG. 3 is a schematic view showing an embodiment of the joint between the insulating ceramic ring and the solid electrolyte and the cathode metal container according to the present invention. The width of the insulating ceramic ring 11 having a radial width of 7 mm and a length of 15 mm is 1.5 mm. mm, a thermocompression bonding member 17, on the surface of the glazing glass 15 on the side of the protrusion 14 having a height of 01.5 mm,
Install the cathode metal container 18, 600 ° C in a hot press, 7.5
Thermocompression bonding is performed under KN conditions.

In this case, the projecting portion 14 has an effect of preventing the outflow of the thermocompression bonding member 17 such as aluminum when the insulation ceramic ring 11 and the cathode metal container 18 are thermocompression bonded.

[Effects of the Invention] As described above, in the sodium-sulfur battery of the present invention, since the insulating ceramic ring has a specific shape, residual stress during bonding at the bonding end portion with the bottomed cylindrical solid electrolyte, and There is an advantage that the joining strength such as the cantilever bending strength can be increased. Further, it is possible to prevent the joining member such as aluminum from flowing out during the thermocompression bonding with the cathode metal container.

[Brief description of drawings]

FIG. 1 is a schematic view showing an embodiment of a joint between an insulating ceramics ring and a bottomed cylindrical solid electrolyte in the present invention, and FIG. 2 is a schematic showing stacking firing using the insulating ceramics ring in the present invention. FIG. 3 is a schematic view showing an embodiment of a joint portion of an insulating ceramic ring with a solid electrolyte and a cathode metal container according to the present invention, and FIG. 4 is a schematic explanatory view showing a structure of a sodium-sulfur battery. . 10 …… Cylindrical solid electrolyte with bottom, 11 …… Insulating ceramic ring, 12 …… Bonding glass, 13 …… Taper part, 14…
… Protrusions, 15 …… Glazing glass, 16 …… Firing stand,
17 ... Thermo-compression bonding member, 18 ... Cathode metal container.

Claims (1)

[Scope of utility model registration request] 1. An anode container for containing molten sulfur and a cathode metal container for storing molten metal sodium are connected and insulated via an insulating ceramic ring, and a bottomed cylinder is provided on the inner peripheral portion of the insulating ceramic ring. In a sodium-sulfur battery, in which the solid electrolyte is fixedly bonded by a bonding glass, and the insulating ceramics ring is thermocompression bonded to the cathode metal container via a thermocompression bonding member. A protrusion is formed on the outer periphery of the insulating ceramic ring on the opening side of the solid electrolyte to prevent protrusion of the thermocompression bonding member, while forming a taper shape in which the portion of the solid electrolyte that is bonded toward the bottom direction expands. And a cathode metal container is in contact with the upper surface of the protrusion, the sodium-sulfur battery.